How to succeed with business oriented IT projects using business process analysis, use cases and requirements management in general.

23/09/2011

Use Case Specification Example

In this post I will show an example of a use case and how to create it. Remember that use cases comes in many detail levels (See overview of Use Case Levels), in this example I will show you a Level2 use case which for example does not specify GUI requirements, error messages and confirmation messages.

Creating a use case specification has three steps:

Create a use case model showing the use cases and actors

Create an overview of the steps (content) of the use case -> here I strongly recommend you to use a model based approach – I prefer creating activity diagrams

Write the use case specification

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In order to give you a fairly simple example I have created a very simple use case model containing only one use case:

From the use case model you can see that the system has one use case only (for simplicity) and that the use case interacts with the actor System Administrator.

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The next thing to do is to create an overview of what goes on inside the use case. That is, what activity steps it contains. The best way to do this is to create an activity diagram (UML notation). The activity diagram is shown below. The advantage of creating an activity diagram is that you will get an overview and be forced to consider validations and error situations.

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Now that you have a use case model and an overview of the steps inside the use case you are dealing with – next thing to do is to write the use case specification. The use case specification will be based on the activity diagram. The main purpose of the use case specification is to specify any pre-conditions that must be met in order to start the use case, specify any business rules related to the use case steps, and specify any post-conditions that will be present after executing the use case.

Especially the business rules are important, since the business rules specify your business requirements. For each step in the use case you need to relate the step to a number of unique business rules – the approach is shown below (as you can see step 20 relates to three business rules (FR1, FR2, FR3):

Welcome to All About Requirements. I hope you are visiting because you, just like me, are absolutely passionate about business process analysis, use cases, and requirements in general. Thank you for visiting.
- John